Colon cancer remains as a major medical challenge in terms of incidence, detection, and cure. The most pressing aspect of the problem is the relatively high mortality rate of 50%, due primarily to the late detection of the disease. Research has detected the presence of potent mutagens in feces and the structure of these compounds, called fecapentaenes, has been elucidated. It seems likely that the presence of these mutagens is directly involved with neoplastic transformations of the colon, but large scale epidemiological studies have not yet been done to establish a causal relationship. The present HPLC technique for fecapentaene detection is quite sensitive, b t is too cumbersome in terms of sample preparation and throughput to utilize in large scale studies. Development of an immunoassay based on an ELISA format would greatly reduce the cost of analysis and would permit analysis of much larger numbers of samples. Once the causal relationship is established, the ELISA could be used for screening of high risk individuals during routine physical examinations. Detection of elevated levels of the mutagens would permit dietary modification and closer screening for detecti n of the actual disease.